With Traffic at a Crawl, Planners Talk of Tunnels
By Dan Weikel, Jeffrey L. Rabin and Daryl Kelley
Times Staff Writers
September 18, 2005
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But Los Angeles is in its 18th year as the nation's most congested metropolis, freeways have little or no space for new lanes and traffic experts are running out of time-shaving options. So civic leaders are joining engineers to consider burrowing the longest highway tunnels in America. "Tunnels," said Wolfgang Roth, a geotechnical engineer working on one possible project in the Antelope Valley, "may finally have their day."
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Giant tunnel-boring machines can drill quickly through the earth, cutting holes 45 feet in diameter. "If the hard rock stands up nice, the boring machine eats right through," said Roth. "Even with the fractured hard rock, as the machine advances, you stabilize the tunnel walls with rock bolts or 'shotcrete,' " he said, using the futuristic term for sprayed concrete. Another benefit of tunnels is that they seem to generate less political dust than surface roads.
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With Southern California's population projected to grow from 18 million to 23 million by 2030 — and with three of four motorists still traveling alone — the average speed on most area freeways during the peak morning commute is expected to drop from 34 mph to 20 mph or less.
Long tunnels, however, are not simple to build. Even the 31-mile English Channel train tunnel, an engineering wonder, took much longer than anticipated and cost double the original estimate. Southern California, with its mountainous terrain, underground aquifers and seismic vulnerabilities, may prove the ultimate testing ground for subterranean highways.
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Indeed, tunnels alone don't have the capacity to end congestion; they must be part of a larger strategy. Los Angeles Mayor Antonio Villaraigosa, for one, wants limited transportation money spent on projects such as light rail and subways. "I think our focus needs to be on getting people out of their single-passenger automobile," he said.
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http://www.latimes.com/news/local/la-me-tunnel18sep18,1,7941391.story?coll=la-headlines-california